The Battle of Poitiers was fought on 19 September 1356 between a French army commanded by King John II and an Anglo-Gascon force under Edward, the Black Prince, during the Hundred Years' War. It took place in western France, 5 miles (8 km) south of Poitiers, when approximately 14,000 to 16,000 French attacked a strong defensive position held by 6,000 Anglo-Gascons.

Nineteen years after the start of the war the Black Prince, the eldest son and heir of the English King, set out on a major campaign in south-west France. His army marched from Bergerac to the River Loire, which they were unable to cross. John gathered a large and unusually mobile army and pursued the Anglo-Gascons, whom he brought to battle. The Anglo-Gascons established a strong defensive position near Poitiers and after unsuccessful negotiations were attacked.

The first French assault included two units of heavily armoured cavalry, a strong force of crossbowmen and many infantry and dismounted men-at-arms. They were driven back by the Anglo-Gascons, who were fighting entirely on foot. A second French attack by 4,000 men-at-arms on foot under John's son and heir Charles, the Dauphin, followed. After a prolonged fight this was also repulsed. As the Dauphin's division recoiled there was confusion in the French ranks: about half the men of their third division, under Philip, Duke of Orléans, left the field, taking with them all four of John's sons. Some of those who did not withdraw with Philip launched a weak and unsuccessful third assault. Those Frenchmen remaining gathered around the King and launched a fourth assault against the by now exhausted Anglo-Gascons, again all as infantry. The French sacred banner, the Oriflamme, was unfurled, the signal that no prisoners were to be taken. Battle was again joined, with the French slowly getting the better of it. Then a small, mounted, Anglo-Gascon force of 160 men, who had been sent earlier to threaten the French rear, appeared behind the French. Believing themselves surrounded, some Frenchmen fled, which panicked others, and soon the entire French force collapsed.

John was captured, as was one of his sons and between 2,000 and 3,000 men-at-arms. Approximately 2,500 French men-at-arms were killed. Additionally, either 1,500 or 3,800 French common infantry were killed or captured. The surviving French dispersed, while the Anglo-Gascons continued their withdrawal to Gascony. The following spring a two-year truce was agreed and the Black Prince escorted John to London. Populist revolts broke out across France. Negotiations to end the war and ransom John dragged out. In response Edward launched a further campaign in 1359. During this, both sides compromised and the Treaty of Brétigny was agreed in 1360 by which vast areas of France were ceded to England, to be ruled by the Black Prince, and John was ransomed for three million gold écu. At the time this seemed to end the war, but the French resumed hostilities in 1369 and recaptured most of the lost territory. The war eventually ended with a French victory in 1453.